Oral appliance



FIG. 1 is a front elevation view of an oral appliance showing my new design;

FIG. 2 is a rear elevation view thereof;

FIG. 3 is a right side elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a top plan view thereof; and

FIG. 6 is a bottom plan view thereof.

FIG. 7 is a front perspective view thereof; and,

FIG. 8 is a rear perspective view thereof.

The broken lines in the drawings illustrate portions of the oral appliance that form no part of the claimed design. 

CLAIM The ornamental design for an oral appliance, as shown and described. 